The invention relates a sheath flow type flow-cell device for photo-particle-analyzers in which fluid carrying particles is made to flow in a capillary flow passage and a light beam is applied thereto and particle analysis is effected on the basis of the strength of the scattering light and/or fluorescence from the particles. The invention further relates to a photo-cell-analyzer and a photo-particle-detector using the flow-cell device.
Heretofore, in order to measure the number, kind, size or shape of particles such as blood cells, photo-particle-analyzers have been used in which fluid carrying particles is made to flow in a capillary flow passage and a light beam is applied thereto and on the basis of the strength of the scattering light and/or fluorescence from the particles, cell analysis, count of particles or the like is effected. In the cell analysis art, such photo-particle-analyzer is called a flow-cytometer. An example of the flow-cytometer is shown in SCIENCE, vol. 150, pages 630-631, 1965. The flow-cell device in the flow-cytometer, as shown in FIGS. 23 and 24, includes a thin bowtie-shaped flow passage. Only suspension of cells is made to flow in the flow passage. Therefore, the flow-cell device has often been clogged during use.
In order to solve the above-mentioned drawback, one method has been disclosed in U.S. Pat. No. 3,873,204. In the method, the suspension of cells (fluid carrying particles) is made to flow together with a physiological salt solution (a sheath fluid) in such a manner that the suspension of cells is surrounded by the physiological salt solution. This method is called as a sheath flow method. The sheath flow method is widely used in cell analyzers as an effective means. In the flow-cell device, a capillary flow passage is formed by a cylindrical glass tube. Therefore, the thickness of the flow-cell device becomes large. Moreover, the entrance portion of the glass tube is made in a funnel shape in order to provide for smooth non-turbulent flow of the fluid at the capillary flow passage, so that the capillary flow passage is made long, for example about 30mm, in order to avoid interference between the objective lens and the funnel-shaped portion of the glass tube. In general, the diameter of the capillary flow passage is made about 300.times.10.sup.-6 m. Therefore, as the length of the capillary flow passage is made longer, the pressure loss becomes greater. Accordingly, the flow-cell device requires pump units having large capacity and a glass tube, piping and the like having high pressure resistance. This makes the flow-cell device itself and the photo-analyzer using the flow-cell device larger. Moreover, as the flow-cell device is made with glass tubes, it is difficult to make the flow-cell device precisely.
Another sheath flow method has also been proposed in Review of Scientific Instruments, Vol. 46, No. 8, pages 1021-1024, August 1975. In the method, the flow-cell device having two flow passages for sheath fluid is used. In the flow-cell device, a first sheath fluid is made to flow in the conical-shaped first flow passage so as to surround sample fluid and a second sheath fluid is made to flow in the conical-shaped second flow passage provided at the circumference of the first flow passage. The flow-cell device can make the flow of the sample fluid stabler but it also has the above-described drawbacks.